Distribution of an air-fuel mixture in a combustion chamber of an internal combustion engine at the time of ignition closely relates to engine performance and emission quality, in particular emission of unburned hydrocarbons, carbon monoxide, and particles. During direct fuel injection, a tumble flow, wherein a vortex is created in a vertical plane of the cylinder, and a swirl flow wherein a vortex is created in a horizontal plane of the cylinder may be introduced to accelerate and assist air-fuel mixture formation in the combustion chamber of the cylinder. The air-fuel mixture may distribute extensively throughout the entire combustion chamber due to the tumble and swirl generated, thereby promoting combustion. Enhancing tumble and swirl ensures fuel availability near a source of ignition, such as a spark plug, which improves combustion efficiency, fuel economy, and power output of the engine.
Other attempts to generate adequate tumble and swirl include a variable intake port geometry to obtain the desired tumble and swirl of the intake air. The variable intake port geometry may include the use of a baffle or shroud in or adjacent the inlet port and the use of a baffle or deflector on the intake valve. Swirl-generating intake ports with various forms of valves, flap valves, vanes, or other devices may also vary the intake port configuration. In one example approach shown in U.S. Pat. No. 4,309,969, a backside of an intake valve includes a rim shroud, directional vanes, and a semi-circular disc fixed to a top edge of the directional vanes. The resulting intake port configuration may generate the desired tumble and swirl in the intake air based on engine operating parameters.
However, the inventors herein have recognized potential issues with such systems. As one example, the adjustment mechanism of valves and vanes to introduce swirl is cumbersome and expensive. Moreover, the structural modification of the intake port may restrict flow, especially during full throttle conditions, which may lead to significant pressure drop. Further, soot may accumulate on the baffle or shrouds, on the valve mechanics, and/or on the vanes, which may cause degradation.
In one example, the issues described above may be addressed by a tumble guide movably housed in a channel of a cylinder head directly below a valve seat configured to interface with an intake valve, and an actuator configured to move the tumble guide to establish contact with an intake valve disc of the intake valve to change an angle of the intake valve disc.
In one example, the tumble guide may be an annulus tumble guide housed in an annulus channel, and a connect rod may couple the annulus tumble guide to the actuator. At a default length of the connect rod, the annulus tumble guide may be fully housed inside the annulus channel, and an opening fluidically connecting an intake port to the combustion chamber may be symmetrical.
The length of the connect rod may be increased or decreased away from the default length to change an angle of the intake valve disc. For example, at an extended length of the connect rod, a first segment of the annulus tumble guide may protrude at least partly out of the annulus channel towards the intake valve disc. The first segment of the annulus tumble guide may come in contact with the intake valve disc when the intake valve is actuated to an open position, changing the angle of the intake valve disc to create a first asymmetrical opening around the intake valve disc. Similarly, at a retracted length of the connect rod, the first segment of the annulus tumble guide moves further back into the annulus channel, away from the intake valve disc, and a second segment of the annulus tumble guide, opposite the first segment, protrudes at least partly outside the annulus channel towards the intake valve disc. The second segment of the annulus tumble guide may come in contact with the intake valve disc when the intake valve is actuated to an open position, changing the angle of the intake valve disc to create a second asymmetrical opening around the intake valve disc.
In this way, changing the angle of the intake valve disc by extending or retracting the connect rod coupled to the annulus tumble guide creates an asymmetrical opening from the intake port to the combustion chamber. The angle of the intake valve may be regulated based on engine operating conditions, for example based on engine load and engine cold start conditions. Introducing intake air through the asymmetrical opening into the combustion chamber may generate desired tumble depending on engine operating parameters. The tumble and swirl generated may enhance fuel combustion, thereby enhancing fuel economy and improving emissions.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.